Screw-propeller.



No. 635,899. Patented Oct. 3|, I899. L. T. ROBERTS.

SCREW PROPELLER.

(Application filed Dec. 20, 189R (No Model.)

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the blades.

UNITED STATES PATENT OFFICE.

LEMUEL T. ROBERTS, OF TOLEDO, OHIO.

SCREW-PROPELLER.

SPECIFICATION forming part of Letters Patent No. 635,899, dated. October31, 1899.

Application filed December 20,1898. Serial No. 699,815. (NomodeL) To allwhom it may concern:

Be it known that I, LEMUEL T. ROBERTS, a citizen of the United States,residing at Toledo, in the county of Lucas and State of Ohio, haveinvented certain new and useful Improvements in Marine Propellers; and Ido declare the following to be a full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which itappertains to make and use the same.

My invention relates to a novel form of marine propeller-wheel; and theobject is to improve the construction and increase the efficiency of thesame.

To these ends the novelty consists in the construction, combination, andarrangement of the same, as will be hereinafter more fully described,and particularly pointed out in the claim.

In the accompanying drawings the same reference characters indicate thesame parts of the invention.

Figure l is a perspective view of my improved propeller-wheel. Fig. 2isa front el'evation of the same. Fig. 3 is an edge view. Fig. 4 is ahorizontal section through one of Fig. 5 is a plan view of one of theblades, taken at a right angle to the face thereof.

In the drawings, 1 represents the hub, 2 2 the radial arms, and 3 3 theapproximately rectangular blades, centrally supported by the arms andhaving their outer edges 6 6 adapted to be arranged at any angle desiredfor power or speed. The base-lines44 of each blade are elliptical andform a continuation of the same plane or in line with a spiral linearound axis equal in length to lead of the wheels circumference. Theedges 5 5 taper to a point and are parallel with each other, as shown inFig. 5, provided the twist is not in them or if taken out of them. Theouter corners 7 7 are curved, as shown, and by referring to Fig. 411.-will be seen that the blade is of a double-convex form in cross-section45 and the oppositely-disposed faces are formed with the same pitch, sothat the wheel operates ex'actly the same in backing as when runningahead.

Another important feature is that each blade has a uniform lead from itsouter edge inwardly to the hub, and in practice a pro peller wheel thusconstructed has in experi mental test developed ten per cent. more speedand the same amount of power with a relatively smaller diameter.

While I have shown my improved propeller as formed with three blades, Ido not wish to be confined to the same, as it is evident that the numberof blades may be increased or di= minished any number from two to fourat will without departing from the spirit of my invention.

In very large propellers each blade, with a corresponding section of thehub, may be built separately and then joined together.

Having thus, fully described my invention,- what I claim, and desire tosecure by Letters Patent, is

, The herein described marine propeller, comprising the hub 1 securedupon the driving-shaft, the integral radial arms 2, 2, extending fromsaidhub 1, the integral double=. convex blades 3 3, formed withapproximately parallel edges 5 5, elliptical outer edges 6, curvedcorners 7 7, and having their oppositely-disposed faces formed with thesame pitch to enable the wheel to operate the same when backing as whenrunning ahead, substantially as specified.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

LEMUEL T. ROBERTS.

Witnesses:

DANIEL H. JAMES, FREDR-ICK J. RHORAR.

